1. Technical Field
The present disclosure relates to systems and methods for controlling an internal combustion engine having two or more spark plugs per cylinder and individual plug control.
2. Background Art
Spark-ignited internal combustion engines may be configured with ignition systems that feature two or more spark plugs for each cylinder to accommodate flexible fuel applications or to provide more ignition energy for leaner air/fuel ratios to improve combustion and enhance fuel economy, for example. Multiple spark plugs may be powered from a common ignition coil and fire at the same time, similar to distributorless ignition systems (DIS) where power paired spark plugs (associated with different cylinders) are fired at the same time with one cylinder in the power stroke and one in the exhaust stroke (waste spark) to improve cost effectiveness of these applications. However, multi-plug applications powered by a common ignition coil present various challenges for implementing ion sensing technology and providing individual spark plug control in a cost-effective manner.
Other solutions for controlling multiple spark plug per cylinder engines include connecting one of the spark plugs to the engine controller and connecting the second spark plug for the same cylinder to the first spark plug using an electric or electronic circuit to provide a delay between firing the first spark plug in response to the command from the controller and the second spark plug in response to the delayed signal through the electronic circuit. Alternatively, each spark plug may have a dedicated control wire from the engine controller to provide increased control flexibility. However, this requires additional controller outputs and associated drivers, which increases complexity and cost.